A stereoscopic display usually presents an observer with images with parallax from individual right and left eye viewpoints. There are several techniques of providing the two eyes of the observer with the parallax images. In a first common stereoscopic technique, the observer utilizes a pair of shutter or 3D glasses which transmit or block light from the viewer's eyes in synchronization with alternating the left/right image display. In a second technique, right eye and left eye images are alternatively displayed and directed towards the respective eyes of the observer but without the use of 3D glasses. This second technique is referred to as autostereoscopic, and is advantageous for stereo 3-dimensional (“3D”) viewing because there is no need for the observer to wear any type of specialized glasses.
A liquid crystal display (LCD) is a sample and hold display device such that the image at any point or pixel of the display is stable until that pixel is updated at the next image refresh time, typically 1/60 of a second or faster. In such a sample and hold system, displaying different images, specifically displaying alternating left and right images for an autostereoscopic display, requires careful timing sequencing of the light sources so that, for example, the left eye image light source is not on during the display of data for the right eye and vice versa.
Ensuring that the right and left light sources are on or off in synchronization with the image display is important to achieve a high quality autostereoscopic image. Further, if the left and right sources provide alternating illumination for a directional backlight structure which extracts light based on the light source end when the right eye image light input surface opposes a left eye image light input surface, light entering either surface can subsequently reflect off the opposing surface and create visual confusion between the left eye image and right eye image, i.e., such reflected light can produce crosstalk (unwanted overlap or interference) between left eye and right eye images, resulting in reduced 3D image quality.